File: t.h

void (*f)(int);

The generated f.java looks as follows:

public interface f {

    void apply(int _x0);
    static MemorySegment allocate(f fi, MemorySession session) {
        return RuntimeHelper.upcallStub(f.class, fi, constants$0.f$FUNC, session);
    }
    static f ofAddress(MemorySegment addr, MemorySession session) {
        MemorySegment symbol = MemorySegment.ofAddress(addr.address(), 0, session);
        return (int __x0) -> {
            try {
                constants$0.f$MH.invokeExact((MemorySegment)symbol, __x0);
            } catch (Throwable ex$) {
                throw new AssertionError("should not reach here", ex$);
            }
        };
    }
}

Note the redundant cast in the line:

                constants$0.f$MH.invokeExact((MemorySegment)symbol, __x0);